In recent years, energy saving has been promoted from a viewpoint of protecting the global environment, and high efficiency and downsizing are also positively directed in the field of electric instruments. Therefore, a non-oriented electrical steel sheet widely used as an iron core material for the electric instrument has been strongly desired to have a high magnetic flux density and a low iron loss.
In order to increase the magnetic flux density in the non-oriented electrical steel sheet, it is effective to improve a texture of a product sheet by decreasing {111} orientation grains and/or increasing {110} or {100} orientation grains. In the conventional production of the non-oriented electrical sheet, therefore, a crystal grain size before a cold rolling is increased, or cold rolling reduction is rationalized.
Another means for improving the texture is a technique of increasing a heating rate in recrystallization annealing. This technique is often used in the production of grain-oriented electrical steel sheets and utilizes the fact that an iron loss is improved by increasing the heating rate in decarburization annealing (primary recrystallization annealing) to increase {110} orientation grains in the steel sheet after the decarburization annealing and refine the structure of the steel sheet after secondary recrystallization (for example, see Patent Document 1). Similarly, a technique for increasing the magnetic flux density by increasing a heating rate in a finish annealing to change the texture in the non-oriented electrical steel sheet is proposed (for example, see Patent Document 2).